Copying process



United States Patent 3,433,951 COPYING PROCESS Satoru Honjo and Kinji Okubo, Kanagawa, Japan, and Toshihiko Nagai, deceased, late of Kanagawa, Japan, by Kenichi Nagai, legal representative, Tokyo, Japan, assignors to Fuji Shashin Film Kabushiki Kaisha, Kanagawa, Japan No Drawing. Filed Dec. 28, 1965, Ser. No. 529,897 US. Cl. 250-65 8 Claims Int. Cl. B41m /00; G03c 11/22 ABSTRACT OF THE DISCLOSURE A copying process comprising a copying material including a support bearing a heat-sensitive layer of a colloidal binder, a material having water of crystallization releasable by heating, and at least one member selected from the group consisting of metallic soaps and Waxes upon an original to be copied, subjecting the laminate of copy material and the original to an infrared exposure and developing with powder developer.

This invention relates to a copying process and more particularly to an improved copying element in a powder developing process.

We have provided a new copying process as described in our prior patent application, U.S. Ser. No. 440,062, filed Mar. 9, 1965, in which a copying element, prepared by applying or vacuum depositing on a support, a compound or a mineral which releases the water of crystallization when heated by the irradiation of infrared rays is placed on an original to be copied. They are subjected to transmittance printing or reflection printing by infrared rays, and then the printed copying element is developed by applying developing powders thereon to give the copy. The copying process utilizes the capability of the copying element to attach the developing powders to the portions thereof corresponding to the pattern of the original, said portions being wetted by the water or crystallization released from the hydrous material of the copying element upon being exposed to infrared rays. However, in prior processes, the copying element is prepared by simply applying on a support a heat-sensitive composition with or without a binder and hence, the surface of the element is inevitably uneven, which results in attaching developing powders to the non-irradiated portions of the reproducing element when it is developed after printing and causing the formation of fogs thereon.

It is an object of this invention to provide a novel process for preparing a copy sheet with reduced fog.

This invention is based on the appreciation of the fact that by incorporating in the heat-sensitive layer of the copying element a material which can increase the nontackiness and the smoothness of the surface of the copying element, whereby the formation of fogs at the nonimage portions is reduced and the relative contrast of the image is increased. Various metallic soaps and various waxes which are solid and water-insoluble at normal temperature are very effective for increasing the nontackiness and smoothness of the surface.

In the operation of this invention, these members are dispersed in the heat-sensitive layer as the fine powders. The fine powders may be incorporated in the coating solution prior to being applied on a support.

A suitable proportion of the member for increasing the smoothness of the surface is 5-40% by weight based on the weight of the heat-sensitive composition. If the content of the composition is less than 5%, the fog density is not reduced markedly and if the content is above 40%, the image density is reduced markedly. Thus, by the 3,433,951 Patented Mar. 18, 1969 process of this invention, a copy having reduced fogs and high contrast is obtained.

As the typical examples of the metallic soaps effective as the component for increasing the smoothness of the surface of the copying element are stearates, palmitates and rosin salts of zinc, cadmium, barium and iron. The metallic soaps and the waxes are used alone or as a mixture thereof.

The following examples illustrate the present invention.

Example 1 Into 200 ml. of water was dissolved 5 g. of gelatin. Into the solution was added 5 g. of sodium acetate (trihydrate) and while stirring to dissolve the acetate 20 ml. of ethanol was added. In ml. of ethanol, 10 g. of barium stearate was dispersed and 30 ml. of the thus obtained dispersion was mixed with the above-prepared solution by stirring thoroughly. The prepared coating dispersion was applied on a triacetyl acetate film base followed by drying such that the coated amount of sodium acetate (tri-hydrate) was 1.2 g./sq. m. For comparison, another heat-sensitive element was prepared by the same conditions except for the addition of barium stearate.

The heat-sensitive film of this invention was placed on an original such that the heat-sensitive layer faced the original and was subjected to reflection printing by exposure to infrared rays from the back (support side) of the film. For the infrared exposure, Thermofax Secretary (a copying machine made by Surnitomo-3M Co.) was used. Thus, a printed heat-sensitive layer was then developed using as the developing powders a toner for a Xerox-914 type copying machine sold by Fuji-Xerox Co.

During the powder developing, the toner is attached to the background portion in addition to the image portion, but when the back surface of the heat-sensitive film was parted, the toner attached to the background portions was removed. After fixing the developed image by placing the film in an atmosphere saturated with trichloroethylene vapor, the fog density of the background substrated with the base density was 0.03.

When the comparative sample was printed, developed and fixed by the same conditions, the net fog density was 0.10.

Example 2 Into 200 ml. of water was dissolved 5 g. of gelatin. Into the solution was added 5 g. of sodium acetate (trihydrate) and while stirring to dissolve the acetate, 30 ml. of ethanol was added. In 100 ml. of ethanol was dispersed 10 g. of zinc palmitate and the mixture was milled for 24 hours in a ball mill. The above-prepared solution was mixed sufficiently with 20 ml. of the disperson by stirring and the mixture was applied on a triacetyl acetate film base followed by drying such that the coated amount of sodium acetate (tri-hydrate) was 1.2 g./sq. m. When the prepared heat-sensitive film was exposed, developed and fixed as in Example 1, the net fog density was measured, which was 0.04.

Example 3 A copying element was prepared as in Example 2 where, however, instead of 10 g. of zinc palmitate, 5 g. of barium stearate and 5 g. of carnauba wax were used. When the heat-sensitive film was exposed, developed and fixed as in Example 1, the net fog density was measured as 0.03.

What we claim is:

1. A copying process comprising the steps of: placing a copying material including a support bearing a heatsensitive layer of a colloidal binder, a material having water of crystallization releasable by heating, and at least one member selected from the group consisting of metallic soaps and waxes upon an original to be copied, subjecting the laminate of copy material and the original to an infrared exposure and developing with powder developer.

2. The copying process as claimed in claim 1 wherein said member is present in the amount of from 5 to 40% by weight of a heat-sensitive layer.

3. The copying process as claimed in claim 1 wherein said metallic soap is selected from metal stearates, metal palmitates and metal salts or rosin.

4. The copying process as claimed in claim 1 wherein said wax is carnauba wax.

5. The copying process as claimed in claim 1 wherein said member is incorporated in said heat-sensitive layer by adding it as a fine powder in a coating composition before the coating composition is applied on the support.

6. A copying element comprising: a support bearing a heat-sensitive layer of a colloidal binder, a material hav- 4 ing water of crystallization releasable by heating, and at least one member selected from the group consisting of metallic soaps and waxes.

7. The copy element as claimed in claim 6 wherein said metallic soap is selected from metal stearates, metal palmitates and metal salts of rosin.

8'. The copy element as claimed in claim 6 wherein said wax is carnauba.

No references cited.

RALPH G. NILSON, Primary Examiner.

A. L. BIRCH, Assistant Examiner.

U.S. Cl. X.R. 

